diff --git a/src/backend/port/atomics.c b/src/backend/port/atomics.c
index 3350fb7df3..439b3c18c7 100644
--- a/src/backend/port/atomics.c
+++ b/src/backend/port/atomics.c
@@ -20,15 +20,32 @@
  */
 #define ATOMICS_INCLUDE_DEFINITIONS
 
+#include "miscadmin.h"
 #include "port/atomics.h"
 #include "storage/spin.h"
 
+#ifdef PG_HAVE_MEMORY_BARRIER_EMULATION
+#ifdef WIN32
+#error "barriers are required (and provided) on WIN32 platforms"
+#endif
+#include <sys/types.h>
+#include <signal.h>
+#endif
+
 #ifdef PG_HAVE_MEMORY_BARRIER_EMULATION
 void
 pg_spinlock_barrier(void)
 {
-	S_LOCK(&dummy_spinlock);
-	S_UNLOCK(&dummy_spinlock);
+	/*
+	 * NB: we have to be reentrant here, some barriers are placed in signal
+	 * handlers.
+	 *
+	 * We use kill(0) for the fallback barrier as we assume that kernels on
+	 * systems old enough to require fallback barrier support will include an
+	 * appropriate barrier while checking the existence of the postmaster
+	 * pid.
+	 */
+	(void) kill(PostmasterPid, 0);
 }
 #endif